The present invention relates to a sewing machine having a movable sewing-material holder, and more particularly to a sewing-material holder which is movable relative to a sewing needle in two directions extending transverse to each other, so as to obtain a seam which follows a predetermined course.
A device of this general type is known from Federal Republic of Germany 32 46 029 Al, equivalent to U.S. Pat. No. 4,406,234, which discloses a device for positioning a sewing part relative to an upwardly and downwardly moving sewing needle. This device consists essentially of a frame which has a carrier and two racks fastened to it which extend at right angles to the carrier. The racks are in engagement with pinions which can be driven by at least one first motor via a step-down gearing, as a result of which the carrier is movable along two guide rails in the longitudinal direction of the sewing-machine arm. A slide which receives the sewing-material holder and to which another rack is fastened on the other side is mounted on a guide rod which extends transverse to the direction of movement of the carrier and is firmly attached to the latter. Said rack is in engagement with another pinion, which can be driven by a second motor. For this purpose, the rack in question is connected in form-locked manner with the corresponding pinion, this connection being disengageable only by time-consuming disassembly.
A disadvantage of the known device resides in the fact that, due to the continuous engagement of the rack with the pinion, the sewing-material holder must be brought back into its predetermined initial position at the end of a sewing operation, after the finished sewn part has been removed from the sewing-material holder, to prepare for the next sewing operation. This necessity causes considerable unproductive idle time to be expended, which idle time is further increased if the sewing machine is to be loaded in continuous alternation with sewing-material holders designed for different seam patterns.